Field of the Invention
The invention relates to a power supply apparatus, and more particularly, relates to a power supply apparatus capable of regulating voltage when offset loading occurs on outputs.
Description of Related Art
In order to provide operating power required by circuit elements inside a computer, mainboards inside the computer are connected to a power supply apparatus. The power supply apparatus may convert AC power into DC power for providing to the mainboards and the peripheral devices of the computer. The current power supply apparatus generally supports a power supply specification known as advanced technology extended (ATX), which is capable of providing a plurality of output voltages with different levels (e.g., +3.3V, +5V, +12V, −5V, −12V), so as to satisfy operation demands for the circuit elements inside the computer.
However, when an offset loading (i.e., a state in which one load corresponding one output voltage is operated in light load (the load operated in small current) while another load is operated in heavy load (the load is operated in large current)) occurs, the power supply apparatus capable of providing the output voltages is generally prone to problem of offset on the output voltages. In other words, when one of said output voltages is raised or dropped, other output voltages may be correspondingly dropped or raised due to influences from said one output voltage. For example, when an output having a rated voltage value being 12V is operated in light load (e.g., current being 1 A), the output voltage thereof may be raised to 12.5V, such that the output voltage of another output having a rated voltage value being 5V may be dropped to 4.5V. The offset on the output voltage may result in that the power supply apparatus fails to meet a required power supply specification when the offset loading occurs.
In conventional technology, said problem of offset on the output voltages is usually solved by connecting resistors in parallel on each of output terminals. Nevertheless, such method merely reduces a voltage on each of the output terminals through a passive circuit architecture, rather than correspondingly adjust the output voltages according to voltage variation at each of the output terminals. In addition, because power loss may occur on the power supply apparatus when connecting the resistors in parallel on the output terminals of the power supply apparatus, an overall power supply efficiency of the power supply apparatus may be affected if said traditional method is adopted to solve the problem of offset on the output voltages when the offset loading occurs.